Sodium ion conduction in perovskite-type sodium lanthanum niobate ceramics

Abstract

The electrical conductivity of NaxLa(1−x)/3NbO3 ceramics has been studied over a composition range of 0.15 ≤ x ≤ 0.45 to identify optimal conductivity conditions and to elucidate the structural and chemical factors affecting the Na+ ion conductivity. The composition with x = 0.25 achieves the highest total conductivity of 7.0 × 10−4 S cm−1 at 350 °C, with Na+ ion transference number of unity. The random distribution of Na, La and vacancy in the two crystallographically independent A sites in perovskite structures significantly impacts the conductivity. In addition, NaxLa(1−x)/3NbO3 perovskite ceramics exhibit high dielectric constants (εr = 220−470) and suppressed electronic conductivity, making them potentially beneficial as an interfacial material to mitigate chemical potential differences between electrolytes and electrode active materials.